Explanation:
The question states that the corporate wireless network has been standardized. By ‘standardized’ it means the wireless network access points are running on hardware from the same vendor. We can see this from the MAC addresses used. The first half of a MAC address is vendor specific. The second half is network adapter specific. We have four devices with MAC addresses that start with 00:10:A1.
The “odd one out” is the device with a MAC address starting FB:90:11. This device is from a different vendor. The SSID of the wireless network on this access point is the same as the other legitimate access points. Therefore, the access point with a MAC address starting FB:90:11 is impersonating the corporate access points. This is known as an Evil Twin.
An evil twin, in the context of network security, is a rogue or fake wireless access point (WAP) that appears as a genuine hotspot offered by a legitimate provider.
In an evil twin attack, an eavesdropper or hacker fraudulently creates this rogue hotspot to collect the personal data of unsuspecting users. Sensitive data can be stolen by spying on a connection or using a phishing technique.
For example, a hacker using an evil twin exploit may be positioned near an authentic Wi-Fi access point and discover the service set identifier (SSID) and frequency. The hacker may then send a radio signal using the exact same frequency and SSID. To end users, the rogue evil twin appears as their legitimate hotspot with the same name.
In wireless transmissions, evil twins are not a new phenomenon. Historically, they were known as honeypots or base station clones. With the advancement of wireless technology and the use of wireless devices in public areas, it is very easy for novice users to set up evil twin exploits.

Incorrect Answers:
B: An initialization vector is a random number used in combination with a secret key as a means to encrypt data. This number is sometimes referred to as a nonce, or “number occurring once,” as an encryption program uses it only once per session.
An initialization vector is used to avoid repetition during the data encryption process, making it impossible for hackers who use dictionary attack to decrypt the exchanged encrypted message by discovering a pattern. This is known as an IV attack. This is not what is described in this question.
C: A rogue access point is a wireless access point that has either been installed on a secure company network without explicit authorization from a local network administrator, or has been created to allow a hacker to conduct a man-in-the-middle attack. Rogue access points of the first kind can pose a security threat to large organizations with many employees, because anyone with access to the premises can install (maliciously or non-maliciously) an inexpensive wireless router that can potentially allow access to a secure network to unauthorized parties. Rogue access points of the second kind target networks that do not employ mutual authentication (client-server server-client) and may be used in conjunction with a rogue RADIUS server, depending on security configuration of the target network. The Evil Twin in this question is a type of rogue access point. However, as the access point is impersonating the corporate network, it is classed as an Evil Twin.
D: A distributed denial-of-service (DDoS) attack occurs when multiple systems flood the bandwidth or resources of a targeted system, usually one or more web servers. Such an attack is often the result of multiple compromised systems (for example a botnet) flooding the targeted system with traffic. When a server is overloaded with connections, new connections can no longer be accepted. The major advantages to an attacker of using a distributed denial-of-service attack are that multiple machines can generate more attack traffic than one machine, multiple attack machines are harder to turn off than one attack machine, and that the behavior of each attack machine can be stealthier, making it harder to track and shut down. These attacker advantages cause challenges for defense mechanisms. For example, merely purchasing more incoming bandwidth than the current volume of the attack might not help, because the attacker might be able to simply add more attack machines. This after all will end up completely crashing a website for periods of time. This is not what is described in this question.